Cartridge positioning cam for automatic revolver guns



I June 30, 1959 J. L. MacDONALD 2,892,385

CARTRIDGE POSITIONING CAM FOR AUTOMATIC REVOLVER GUNS Filed Aug. 29. 1956 Fig-3.-

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CARTRIDGE POSITIONING CAM FOR AUTOMATIC REVOLVER GUNS John L. MacDonald, Chicago, 111., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Army Application August 29, 1956, Serial No. 606,939 1 Claim. (Cl. 89-137) My invention relates to revolver-type automatic guns having an anvil with an insulated firing pin therein for discharge of cartridges and more particularly to a device for guiding the cartridges into position for contact with the firing pin.

Such guns usually include a recoil unit with a pedestal disposed thereon, and a drum with a plurality of radiallydisposed chambers for the cartridges is journaled at one end in the pedestal for rotation of the chambers through a firing station in axial alignment with the firing pin. An anvil is disposed in the pedestal for axial alignment with a chamber in the firing station, and an electrically insulated firing pin is disposed in the anvil for slidable operation to a projection position for electrical engagement with the primers of the chambered cartridges for discharge thereof.

Accumulations of tolerances in the drum and the cartridges have sometimes caused the cartridges to be chambered too deeply in the drum for the required electrical engagement between the pimers and the firing pin, and it is an object of my invention to provide a device for guiding the cartridges to insure such engagement.

Another object of my invention is to provide a device on the recoil unit for properly positioning the cartridges in the drum during movement into the firing station.

Other aims and objects of my invention will appear in the following explanation.

In carrying out my invention, a guide is secured to the recoil unit forwardly of the anvil and below the firing pin therein and is spaced from the pedestal to provide a groove for retaining the primers of the cartridges in engagement with the firing pin in the projection position thereof. The entrance end of the cartridge-retaining groove is provided with a cam surface for guiding the cartridge rearwardly into position to be contacted by the firing pin.

For a more complete understanding, reference is directed to the following description and the accompanying drawing in which:

Fig. 1 is a side elevational view partially in cross-section of a revolver-type automatic gun incorporating my invention;

Fig. 2 is a view along line 22 of Fig. 1; and

Fig. 3 is a view along line 3-3 of Fig. 2.

Accordingly, an automatic gun 12 is provided with a recoil unit 14, a pedestal 16 and a drum 18 provided with a plurality of radially-disposed firing chambers 20 for cartridges 22. Pedestal 16 is secured to the rear end of recoil unit 14 and serves as the rear journal for drum 18 which is arranged to be rotated by a longitudinally reciprocal actuator (not shown) so that each of the chambers therein successively passes through a firing station in alignment with a firing pin 28 in the bottom of pedestal 16.

An anvil 26 is disposed in pedestal 16 for concentric alignment with the firing chamber in the firing station, and firing pin 28 is slidably disposed in the center of the anvil to project forwardly therefrom so as to engage the primer in the rear end of the chambered cartridge in the firing station. The firing pin is retractable in order to 2,892,385 Patented June 30, 1959 prevent interference with the rotation of drum 18 responsive to the discharge of the cartridges.

Cartridges 22 are rammed into chambers 20 in the stations rotationally preceding the firing station, and a guide for the cartridges comprises an arcuately formed member 30 secured to the recoil unit by means of suitable pins 40. One end of member 30 lies in front of the lowermost peripheral portion of anvil 26 and extends concentrically With the periphery of the drum and in a clockwise direction as viewed looking toward the muzzle end of the gun to terminate substantially beyond anvil 26. The upper edge of member 30 is formed with a shoulder 42 which in conjunction with the front face of recoil unit 14 forms a groove 44 adapted to receive the projecting rim 38 of a cartridge case 22 during movement thereof into and ough the firing station. At the same time, the upper surface of member 30 is shaped to fit snugly but slidingly into the annular extraction groove 36 formed in case 22 immediately forwardly of rim 38 thereon as best shown in Fig. l. The entrance end of groove 44 is provided with a cam surface 32 adapted to bear against the front face of cartridge case rim 38 in the event the cartridge has been forced too far forwardly into chamber 20 during the ramming operation. Thus, as cartridge 22 is carried into the firing station by the rotation of drum 18, cam surface 32 forces the base of cartridge 22 against anvil 26 and groove 44 retains the cartridge in such engagement to ensure the electrical contact between the tip of firing pin 28 and the primer 34 at the instant of firing.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claim is intended to include such variations.

I claim:

In an automatic gun having a recoil unit and an electrically insulated firing anvil therein, a firing pin disposed in the anvil for electrical contact with the primer in a cartridge case of the type wherein an annular extractor groove at the rear end thereof forms a projecting rim, a drum rotatably mounted in the recoil unit forwardly of the anvil, and at least one cartridge-holding chamber in the drum adapted to be rotated through a firing station in axial alignment with the firing pin for discharge of the cartridge in the chamber, the improvement of means for insuring electrical contact between the firing pin and the cartridge primer despite the chambering of the cartridge to a greater than normal depth in the drum, comprising an arcuate guide member fixedly secured to the recoil unit to lie forwardly of and adjacent the lowermost portion of the anvil and extend outwardly therebeyond concentrically with the drum into the path of movement of the chambered cartridge, a shoulder in the upper edge of said member facing the recoil unit and spaced apart therefrom to form a groove adapted to receive the rim of the chambered cartridge case, and a cam surface on said guide member adjacent the entrance end of said groove and positioned to bear against the front face of the cartridge case rim and force the primer end against the anvil, the remaining portion of said groove being adapted to maintain the contact of the primer end of the cartridge with the anvil up to and during the discharge thereof by the firing pin.

References Cited in the file of this patent UNITED STATES PATENTS 1,805,601 Ross May 19, 1931 1,502,676 Kewish July 29, 1954 2,805,604 Humphrey Sept. 10, 1957 FOREIGN PATENTS 863,614 Germany Ian. 19, 1953 

